Auxiliary contact system for electromagnetic switching devices

ABSTRACT

A contact sequencing arrangement accomplished by a lost motion drive connection between the armature and the auxiliary contact system in conjunction with a permanent magnet detent system for the movable member of the auxiliary contact system wherein the main contacts of the relay make before the auxiliary contacts make and break before the auxiliary contacts break.

United States Patent Halbeck 51 Jan. 23, 1973 [54] AUXILIARY CONTACT SYSTEM FOR ELECTROMAGNETIC SWITCHING DEVICES [72] lnventor: Werner B. Halbeck, Cedarburg,

Wis.

[73] Assignee: Cutler-Hammer, Inc., Milwaukee,

Wis.

[22] Filed: June 25, 1971 [21] Appl. No.: 156,681

[52] US. Cl. ..335/136, 200/166, 335/80 [51] Int. Cl. ..I'I0lh 3/48 [58] Field of Search ..335/179, 136, 128, 129, 79,

[5 6] References Cited UNITED STATES PATENTS 2,854,547 9/1958 Little ..335/80 3,056,001 9/1962 Fichter ..200/67 F 2,782,278 2/1957 Peters ..200/67 F 2,641,664 6/1953 Knutson ..200/67 F 2,427,719 9/1947 Exner ..335/80 Primary Examiner-Har0ld Broome Attorney-I-1ugh R. Rather et al.

[57] ABSTRACT A contact sequencing arrangement accomplished by a lost motion drive connection between the armature and the auxiliary contact system in conjunction with a permanent magnet detent system for the movable member of the auxiliary contact system wherein the main contacts of the relay make before the auxiliary contacts make and break before the auxiliary contacts break.

5 Claims, SDrawing Figures Pmminmzsaszs 3,713,055

SHEET 2 UF 2 719.2 Jays AUXILIARY CONTACT SYSTEM FOR ELECTROMAGNETIC SWITCHING DEVICES BACKGROUND OF THE INVENTION This invention relates to electromagnetic switching devices of the rocking armature type and particularly to auxiliary contact assemblies therefor.

It is a well known practice to provide electromagnetic contactors and relays of the foregoing type with one or more auxiliary contact assemblies which are operated by the armature of the device. The auxiliary contacts are adjusted to operate in some sequential relationship to the main power contacts of the switching device, i.e.; make before the main contacts make or break before the main contacts break. This disclosure incorporates both of the aforementioned contact operating relationships in a single auxiliary contact assembly which heretofore has not been readily attainable using conventional design practices.

SUMMARY OF THE INVENTION It is a primary object of this invention to provide an auxiliary contact system for an electromagnetic switching device wherein the main contacts of the device make before the auxiliary contacts make and break before the auxiliary contacts break.

It is a further object of this invention to provide an auxiliary contact assembly of the aforedescribed type which has improved contact operation.

It is still a further object of this invention to provide an auxiliary contact system of the aforedescribed type embodied in one single pole, double throw auxiliary contact assembly.

These and other objects and advantages of this invention will be come more apparent in the following specification and claims when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of an hermetically sealed electromagnetic contactor incorporating the auxiliary contact structure of this invention and shown in one extreme operating position of the contactor; and

FIGS. 2-5 are sequential operating views of a portion of the contactor mechanism shown in FIG. 1 illustrating the operation of the auxiliary contact system with respect to the operation of the contactor in moving from the first operating position shown in FIG. 1 to the other extreme operating position thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings and particularly FIG. 1, there is shown a single pole double throw hermetically sealed electromagnetic contactor. The enclosing structure for the contactor is illustrated in cross-section and comprises a metallic shell 2 having an outwardly extending flange 2a around the open upper end thereof and a metallic cover 4 having an outwardly extending flange 4a surrounding the open lower end thereof and mating with the flange 2a of shell 2. The flanges 2a and 4 a are secured together by a continuous weld formed therearound. A mounting plate 6 is welded to the lower end of shell 2 for mounting the contactor on a panel.

Cover 4 is provided with three threaded terminal assemblies 8, 10 and 12 projecting therethrough, the assemblies being of the type described in the J. E. Davies et al. US. Pat. No. 2,951,133 issued Aug. 30, 1960 and assigned to the assignee herein. As is also described in the above referenced patent, a coating of glass 14 is fused to the cover 4 at both sides thereof and around the terminal assemblies to provide an hermetic seal around each of the terminals.

A magnet assembly 16 is centrally mounted within the shell 2. The assembly 16 includes an L-shaped magnet frame 18 upon which a core 20 is mounted. The core projects through an axial opening in a coil 22 to secure the latter upon the frame 18. A permanent magnet 24 is also mounted upon the frame 18 at the righthand end thereof to project upwardly therefrom. A pair of pole pieces 26 and 28 are secured to the upper ends of the upstanding leg of frame 18 and the permanent magnet 24, respectively. To complete the magnet assembly 16, a V-shaped armature 30 is mounted upon the upper surface of the core 20 at the center of the magnet assembly to rock thereon between the pole pieces 26 and 28.

An insulating contact carrier 32 is mounted to the top surface of armature 30. Upstanding posts 34 and 36 are mounted in the contact carrier 32 at the right and left-hand ends thereof, respectively, to support bridging contact assemblies 38 and 40 thereon, respectively. While not specifically shown in the drawings, bridging contact assemblies 38 and 40 have centrally located openings through which the respective posts 34 and 36 loosely project to permit sliding movement of the bridging contacts upon the posts, the openings and posts being cooperatively keyed to prevent rotational movement of the bridging contacts about the respective post. Helical compression springs 42 and 44 are disposed about posts 34 and 36, respectively, to bear between the upper surface of the respective bridging contact assembly and a washer-retaining ring combination attached to each post near the outer end thereof. The springs 42, 44 bias the respective bridging contact assemblies 38 and 40 downwardly along the respective posts'to rest upon an annular shoulder formed on each post or to provide contact pressure as the bridging contacts engage the stationary contacts.

Terminal assembly 12 represents the common terminal for the contactor and has an interior shank portion extending through cover 4 to depend toward shell 2. At the innermost end of the shank portion terminal 12 is provided with a contact plate 46 having co-planar arm portions 48 and 50 extending to the right and left, respectively, to underlie the rear end portions of the bridging contact assemblies 38 and 40, respectively.

Terminal assemblies 8 and 10 also have interior shank portions projecting toward and into shell 2, although these portions have been broken away in the drawing to more clearly illustrate the bridging contact mounting arrangement. Contact plates 52 and 54 are provided at the inner ends of terminal assemblies 8 and 10, respectively, to extend rearwardly toward and be co-planar with the respective arm portions 48 and 50 of contact plate 46, the plates 52 and 54 underlying the forward ends of bridging contact assemblies 38 and 40, respectively. Each of the bridging contact assemblies 38 and 40 and the respective contact plates 48, 50, 52

and 54 have cooperating contact segments secured thereto for improved electrical engagement at the points of contact.

In the deenergized condition of the contactor as illustrated in FIG. 1, the armature 30 lays over to the right to be in engagement with pole piece 28 by virtue of the permanent magnet 24. In this position the bridging contact assembly bridges the portion 48 of common terminal l2 and the contact plate 52 of terminal 8. When coil 22 is energized to operate the contactor the annature 30 rocks over to the left to engage pole piece 26, thereby driving bridging contact assembly 40 into engagement with the portion 50 of contact plate 46 and the contact plate 54. The bridging contact assembly 38 is simultaneously lifted from the stationary contacts on the right-hand side and the completed circuit for the contactor is changed from terminals 12-8 to terminals 12-10.

The contactor is also provided with an auxiliary contact assembly for the purpose of switching circuits of lesser amperage without providing an entire auxiliary relay device. The auxiliary contact assembly is driven off the movable armature 30 and therefor may be readily adjusted to provide operation in a prescribed relation to the operation of the main contacts of the contactor.

Referring again to FIG. 1 of the drawings, the insulating contact carrier 32 is provided with a forwardlyextending depending leg 56 having an arcuate rod 58 attached at the end thereof. Rod 58 is formed to be concentric about the axis of rotation of armature 30. A pair of slide blocks 60 and 62 having circular openings therethrough for receiving the rod 58, are mounted on the rod 58 near one end and fixed in location thereon by set screws provided in each block. Each block 60 and 62 is further provided with an actuator pin 64 and 66, respectively, projecting rearwardly therefrom toward the magnet assembly 16.

The auxiliary contact assembly is mounted upon an insulating board 68 which is attached to the forward side of the magnet assembly 16 by suitable means (not shown). Board 68 has a first forwardly projecting boss 70 located at the top thereof and a second forwardly projecting boss 72 located along the right-hand edge thereof. A first stationary contact segment 74 is mounted upon a formed leaf spring which is mounted through the boss 70 to depend freely along and spaced from the front surface of board 68. A second stationary contact segment 76 is mounted upon a leaf spring which in turn is mounted through the boss 72 to extend along the front of the board 68 and position the contact segment 76 in arcuately spaced, face-to-face relationship with the contact segment 74.

The movable contact member for the auxiliary contact assembly comprises a double-faced contact segment 78 mounted through a leaf spring member 80 which is mounted through the boss 70 to position the segment 78 between the segments 74 and 76. The leaf spring 80 has a double reverse bend formed therein between the boss 70 and the contact segment 78 to improve the wiping action between the contacts in operation thereof. Spring 80 also has an extension depending between and beyond the actuator pins 64 and 66. A block 82 of magnetic iron is attached to the lower end of the depending portion of the leaf spring 80 and is positioned between two permanent magnets 84 and 86 mounted on the front surface of board .68.

As will be brought out more clearly in later description, the function of the permanent magnets 84 and 86 andblock 82 is to delay the separation of the respective auxiliary contacts until after the main power contacts of the contactor have separated. By locating the point of engagement of the actuator pins 64 and 66 with the movable leaf spring between the contact segment 78 and the block 82, contact pressure for the auxiliary contacts is provided by overtravel of the actuator pins 64 or 66.

Referring additionally to FIGS. 2 through 5 of the drawings, the operation of the contactor and auxiliary contact assembly from the deenergized position of the contactor shown in FIG. 1 to the energized position thereof shown in FIG. 5 will be described. Upon enerv gization of coil 22 the armature 30 begins to rock over to the left toward pole piece 26. Initial movement thereof (FIG. 2) causes the annular shoulder on post 34 to engage the underside of bridging contact assembly 38 and thereby move the latter upwardly off the contact segments on plate 52 and portion 48. Simultaneously with this movement the actuator pin 64 moves away from the righthand surface of leaf 80 to release the contact pressure from the normally closed auxiliary contact pair 74, 78. The iron block 82 remains attracted to the permanent magnet 86 to hold the leaf 80 in position and maintain the electrical engagement between the contacts 74, 78.

Referring now to FIG. 3, it may be seen that as the armature 30 rocks further toward the left the actuator pin 66 engages the leaf 80 at the left-hand surface thereof and drives the movable contact 78 out of engagement with the contact 74. Continued movement of the armature 30 causes the bridging contact assembly 40 to electrically engage with the contact segments on plate 54 and portion 50 as seen in FIG. 4 to complete a circuit between terminals 12 and 10 of the contactor; however, it may also be seen in FIG. 4 that the pin 66 has not yet driven the leaf 80 far enough to cause engagement between the normally open auxiliary contact pair 76, 78.

AS the armature 30 moves to its fully seated energized position (see FIG. 5) the spring 44 is compressed by the bridging contact assembly 40 to provide contact pressure therefor. This last increment of armature movement causes the pin 66 to drive the contact 78 into engagement with the contact 76 to close the circuit therebetween, to drive the iron block 82 into contact with permanent magnet 84 and to deflect the leaf 80 in the area between block 82 and the contact 78 to pro vide contact pressure for the latter.

The same sequence of operation exists for the reverse operation of the contactor, that is the movement of the armature from the energized position of FIG. 5 to the deenergized position of FIG. 1. Such movement would first reduce the contact pressure on the main contactor bridging contacts 40 and on the normally open auxiliary contacts 78, 76, then separate the bridging contacts 40 from the segments on plate 54 and portion 50, next cause pin 64 to drive the auxiliary contacts 78, 76 open, subsequently cause the closing of bridging contact 38 upon the contact segments on plate 52 and portion 48 and finally cause pin 64 to drive the contact 78 into engagement with the contact 74 and iron block 82 into engagement with permanent magnet 86.

While only one auxiliary contact assembly is shown herein, it is to be understood that a mirror image auxiliary contact assembly could be provided at the left of board 68 in FIG. 1. In that instance, a second pair of slide blocks and actuator pins would be provided on the bar 58. Also the same arrangement may be duplicated on the rear side of the magnet assembly 16, thereby affording as many as four, single pole double throw, auxiliary contact assemblies for the contactor.

Iclaim:

i. In combination with a double throw electromagnetic switching device having normally open and normally closed contact sets and movable armature means operatively connected to said contact sets movable between first and second operating positions to affect reverse actuation of said contact sets; an auxiliary contact system comprising a pair of stationary contacts mounted in spaced apart relation; movable contact means movable between said stationary contacts to electrically engage an alternate one thereof and comprising a leaf spring supported at one end to permit oscillatory movement at the other end thereof and having contact' surfaces disposed on opposite sides of said leaf spring inwardly of the free end thereof in operative alinement with said stationary contacts; cooperating magnetic means comprising a first portion carried on the free end of said leaf spring and a second portion comprising a pair of elements mounted in spaced apart relation at opposite sides of said first portion, the latter being movable with said movable contact means to magnetically engage a respective one of said pair of elements when said movable contact means is in electrical engagement with a respective one of said stationary contacts; drive means operably connecting said armature means to said leaf spring to affect electrical engagement of said movable contact with a respec I tive one of said stationary contacts when said armature is in one of said first or second operating positions, said drive means being operatively connected to said leaf spring between said contact surfaces and said magnetic means'first portion and deflecting said leaf spring in the direction of the respective auxiliary contact engagement when said armature is in one of said first or secondoperating positions to provide contact pressure for the respective engaged auxiliary contacts;

wherein the magnetic attraction between said first portion and a respective element of said second portion maintains said movable contact means in electrical engagement with a respective one of said stationary contacts until said armature means moves an amount sufficient to affect actuation of said normally closed contact set; said magnetic attraction further delaying movement of said movable contact means toward the respective opposite one of said stationary contacts to permit said armature means to affect engagement of said movable contact means with said respective opposite one of said station contacts, 2. The combination according to claim 1 wherein the connection between said drive means and said leaf spring is a lost motion connection comprising extension means extending from said armature means and projecting along the line of movement thereof, a pair of drive pins independently adjustably mounted on said extension means, said drive pins projecting along opposite sides of said leaf spring and adjusted to provide a predetermined amount of movement of said armature means before a respective one of said drive pins abuts the respective side of said leaf spring to drive the latter, said predetermined movement being an amount sufficient to affect actuation of said normally open or said normally closed contact set.

3. The combination according to claim 2 wherein initial movement of said armature means from one of said first or second operating positions toward the other affects movement of a respective one of said drive pins away from said leaf spring to relieve the deflection thereof and thereby reduce the contact pressure for the respective engaged auxiliary contacts, said magnetic means first portion cooperating with a respective one of said elements of said magnetic means second portion to maintain electrical engagement between the said respective engaged auxiliary contacts until said armature means moves a further distance sufficient to actuate a respective one of said contact sets and move the other of said drive pins into engagement with the opposite side of said leaf spring.

4. The combination according to claim 3 wherein said leaf spring is formed with a pair of adjacent reversely-bent loops intermediate said supported end and said contact surfaces to serve as a resilient hinge for said leaf spring. a I

5. The combination according to claim 4 wherein said armature means is rotatable and said extending means projects radially therefrom through the axis of rotation thereof, said extension means also comprising an arcuate rod carried at the outermost end and formed radially about said axis of rotation to project along the line of movement of said armature means. 

1. In combination with a double throw electromagnetic switching device having normally open and normally closed contact sets and movable armature means operatively connected to said contact sets movable between first and second operating positions to affect reverse actuation of said contact sets; an auxiliary contact system comprising: a pair of stationary contacts mounted in spaced apart relation; movable contact means movable between said stationary contacts to electrically engage an alternate one thereof and comprising a leaf spring supported at one end to permit oscillatory movement at the other end thereof and having contact surfaces disposed on opposite sides of said leaf spring inwardly of the free end thereof in operative alinement with said stationary contacts; cooperating magnetic means comprising a first portion carried on the free end of said leaf spring and a second portion comprising a pair of elements mounted in spaced apart relation at opposite sides of said first portion, the latter being movable with said movable contact means to magnetically engage a respective one of said pair of elements when said movable contact means is in electrical engagement with a respective one of said stationary contacts; drive means operably connecting said armature means to said leaf spring to affect electrical engagement of said movable contact with a respective one of said stationary contacts when said armature is in one of said first or seconD operating positions, said drive means being operatively connected to said leaf spring between said contact surfaces and said magnetic means first portion and deflecting said leaf spring in the direction of the respective auxiliary contact engagement when said armature is in one of said first or second operating positions to provide contact pressure for the respective engaged auxiliary contacts; wherein the magnetic attraction between said first portion and a respective element of said second portion maintains said movable contact means in electrical engagement with a respective one of said stationary contacts until said armature means moves an amount sufficient to affect actuation of said normally closed contact set; said magnetic attraction further delaying movement of said movable contact means toward the respective opposite one of said stationary contacts to permit said armature means to affect engagement of said movable contact means with said respective opposite one of said stationary contacts.
 2. The combination according to claim 1 wherein the connection between said drive means and said leaf spring is a lost motion connection comprising extension means extending from said armature means and projecting along the line of movement thereof, a pair of drive pins independently adjustably mounted on said extension means, said drive pins projecting along opposite sides of said leaf spring and adjusted to provide a predetermined amount of movement of said armature means before a respective one of said drive pins abuts the respective side of said leaf spring to drive the latter, said predetermined movement being an amount sufficient to affect actuation of said normally open or said normally closed contact set.
 3. The combination according to claim 2 wherein initial movement of said armature means from one of said first or second operating positions toward the other affects movement of a respective one of said drive pins away from said leaf spring to relieve the deflection thereof and thereby reduce the contact pressure for the respective engaged auxiliary contacts, said magnetic means first portion cooperating with a respective one of said elements of said magnetic means second portion to maintain electrical engagement between the said respective engaged auxiliary contacts until said armature means moves a further distance sufficient to actuate a respective one of said contact sets and move the other of said drive pins into engagement with the opposite side of said leaf spring.
 4. The combination according to claim 3 wherein said leaf spring is formed with a pair of adjacent reversely-bent loops intermediate said supported end and said contact surfaces to serve as a resilient hinge for said leaf spring.
 5. The combination according to claim 4 wherein said armature means is rotatable and said extending means projects radially therefrom through the axis of rotation thereof, said extension means also comprising an arcuate rod carried at the outermost end and formed radially about said axis of rotation to project along the line of movement of said armature means. 